Statistics in sports is about to hit a whole new level. A new generation of wearable monitors that measure heart rate, electrical activity in the heart, lung capacity, metabolism, and other metrics is allowing scientists to study athletes' physiology as they play.

The data has obvious potential to enhance players' health, and to help trainers tailor workouts, but device makers and the sports industry seem most excited about the prospects for entertainment. They are already working on ways to display the data during games, in stadiums and on television, giving fans unprecedented insight into players.

Last February, when the NFL held its annual scouting combine to assess the top-ranked college players, the highest-profile draftees wore special shirts fitted with sensor technology, developed by Under Armour and Zephyr Technologies. The players' data—such as acceleration during the first 10 yards of the 40-yard dash—was recorded as they ran through the various physical trials.

"Millions of dollars in decisions are made based on the 40-yard dash," says Leslie Saxon, a cardiologist and director of the center for body computing at the University of Southern California, who led a panel on sports and body sensors at a conference held there last week. "If you can get much more sophisticated statistics on body position, physiology, and mechanics, I think it could play a big role."

Zephyr started out six years ago developing wearable monitors for the Special Forces. But thanks to cheaper sensors and wireless radio technology—changes that have already spawned a new movement in self-monitoring among ordinary people—the company is moving toward the professional sports and consumer market.

"Athletes want feedback immediately, and they get competitive quickly," says Brian Russell, Zephyr's CEO. "I am convinced it helps them perform better because they are getting measured."

The latest version of the technology is made up of a sleek disc—about the size of a compact—that holds sensors for heart rate, temperature, and movement, along with a power source, Bluetooth transmitter, and memory storage. The device is paired with fabric electrodes embedded in a chest strap, shirt, or bra. In conjunction with sophisticated software, the technology can measure heart vitals, as well as anaerobic threshold and aerobic capacity.

Russell says more than 50 college and professional sports teams around the country, from football and basketball to volleyball and hockey, are using the technology to monitor their players. The data helps with the athletes' safety—heart rate can be used to predict dehydration, for example, which is linked to sudden cardiac death in young athletes. And trainers aim to use it to make workouts more efficient for individual players.